Control system for work machine, method, and work machine

Abstract

A controller for a work machine acquires current topography data indicating a current topography to be worked. The controller determines a target design topography based on the current topography. The target design topography indicates a target trajectory of a work implement. The controller generates a command signal to operate the work implement to excavate the current topography according to the target design topography. The controller acquires excavated topography data indicating a current topography that has been excavated. The controller modifies the target design topography to move the target design topography upwardly based on the excavated current topography.

The invention claimed is: 
     
       1. A control system for a work machine including a work implement, the control system comprising:
 a controller configured to
 acquire current topography data indicating a current topography, 
 determine a target design topography indicating a target trajectory of the work implement based on the current topography, 
 generate a command signal to operate the work implement to excavate the current topography according to the target design topography, 
 acquire excavated topography data indicating an excavated current topography, and 
 modify the target design topography to move the target design topography upwardly based on the excavated current topography. 
 
 
     
     
       2. The control system for a work machine according to  claim 1 , wherein
 the excavated topography data indicates a depth of the excavated current topography, and 
 the controller is further configured to
 determine whether a depth of the excavated current topography is shallower than the target design topography, and 
 modify the target design topography to move the target design topography upwardly when the depth of the excavated current topography is shallower than the target design topography. 
 
 
     
     
       3. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to modify the target design topography to move the target design topography upwardly according to the depth of the excavated current topography when the depth of the excavated current topography is shallower than the target design topography. 
 
     
     
       4. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to modify the target design topography to be in contact with the excavated current topography when the depth of the excavated current topography is shallower than the target design topography. 
 
     
     
       5. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to modify the target design topography to pass through a position at or above a lowest point of the excavated current topography when the depth of the excavated current topography is shallower than the target design topography. 
 
     
     
       6. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to determine that the depth of the excavated current topography is shallower than the target design topography when a distance between the excavated current topography and the target design topography is equal to or greater than a predetermined threshold in a gravity direction. 
 
     
     
       7. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to determine that the depth of the excavated current topography is shallower than the target design topography when a distance between the excavated current topography and the target design topography is equal to or greater than a predetermined threshold in a normal direction of the target design topography. 
 
     
     
       8. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to determine that the depth of the excavated current topography is shallower than the target design topography when a distance between the excavated current topography and the target design topography is equal to or greater than a predetermined threshold at a position farthest from the target design topography between a current excavating end position or a previous excavating start position and a lowest point of the excavated current topography. 
 
     
     
       9. The control system for a work machine according to  claim 2 , wherein
 the controller is further configured to determine that the depth of the excavated current topography is shallower than the target design topography when a distance of a portion along the target design topography, the portion being positioned above the target design topography between a lowest point of the excavated current topography and an excavating end position is equal to or greater than a predetermined threshold. 
 
     
     
       10. A method executed by a controller for controlling a work machine including a work implement, the method comprising:
 acquiring current topography data indicating a current topography to be worked; 
 determining a target design topography indicating a target trajectory of the work implement based on the current topography; 
 generating a command signal to operate the work implement to excavate the current topography according to the target design topography; 
 acquiring excavated topography data indicating an excavated current topography; and 
 modifying the target design topography to move the target design topography upwardly based on the excavated current topography. 
 
     
     
       11. The method according to  claim 10 , wherein
 the excavated topography data indicates a depth of the excavated current topography, 
 the method further comprising
 determining whether the depth of the excavated current topography is shallower than the target design topography; and 
 modifying the target design topography to move the target design topography upwardly when the depth of the excavated current topography is shallower than the target design topography. 
 
 
     
     
       12. The method according to  claim 11 , wherein
 the target design topography is modified to move the target design topography upwardly according to the depth of the excavated current topography when the depth of the excavated current topography is shallower than the target design topography. 
 
     
     
       13. The method according to  claim 11 , wherein
 the target design topography is modified to be in contact with the excavated current topography when the depth of the excavated current topography is shallower than the target designed topography. 
 
     
     
       14. The method according to  claim 11 , wherein
 the target design topography is modified to pass through a position at or above a lowest point of the excavated current topography when the depth of the excavated current topography is shallower than the target design topography. 
 
     
     
       15. The method according to  claim 11 , wherein
 the depth of the excavated current topography is determined to be shallower than the target design topography when a distance between the excavated current topography and the target design topography is equal to or greater than a predetermined threshold in a gravity direction. 
 
     
     
       16. The method according to  claim 11 , wherein
 the depth of the excavated current topography is determined to be shallower than the target design topography when a distance between the excavated current topography and the target design topography is equal to or greater than a predetermined threshold in a normal direction of the target design topography. 
 
     
     
       17. A work machine comprising:
 a work implement; and 
 a controller configured to control the work implement, the controller being configured to
 acquire current topography data indicating a current topography to be worked, 
 determine a target design topography indicating a target trajectory of the work implement based on the current topography, 
 generate a command signal to operate the work implement to excavate the current topography according to the target design topography, 
 acquire excavated topography data indicating an excavated current topography, and 
 modify the target design topography to move the target design topography upwardly based on the excavated current topography. 
 
 
     
     
       18. The work machine according to  claim 17 , wherein
 the excavated topography data indicates a depth of the excavated current topography, and 
 the controller is further configured to
 determine whether the depth of the excavated current topography is shallower than the target design topography, and 
 modify the target design topography to move the target design topography upwardly when the depth of the excavated current topography is shallower than the target design topography. 
 
 
     
     
       19. The work machine according to  claim 17 , wherein
 the controller is further configured to modify the target design topography to move the target design topography upwardly according to the depth of the excavated current topography when the depth of the excavated current topography is shallower than the target design topography. 
 
     
     
       20. The work machine according to  claim 17 , wherein
 the controller is further configured to modify the target design topography to be in contact with the excavated current topography when the depth of the excavated current topography is shallower than the target design topography.